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The paper proposes o method of solving differential equations using Runge-Kutta method and presents an application made in a Visual programming language that solves two differential equations step by step drawing the graph obtained for two electrically charged particles that interact by their electrical fields

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The paper proposes a method of calculation and rapid sizing of power circuits of electrical panels using a program made in-house. The proposed application has a friendly and very intuitive graphical interface, being easy to use due to the intelligent way of making the selection and data entry. This application emerged in response to the real need for fast and accurate sizing of low voltage electrical switchboards used in industry. The real help is provided by the mechanism that allows frequent and rapid modification of the technical solution to adapt to the ever-changing requirements dictated by the stages in the development of electrical projects.The operation of the program is based on the existence of an internal database materialized using several data tables containing various types of electrical consumers, switching and protection equipment and a series of standardized power cables from which they are automatically selected. The selection is made based on sizing and verification calculations with the help of intelligent selection methods so that only the equipment that matches the data provided by the user are selected ensuring an additional verification of the various omissions that may occur.The application is useful for designing of a new installation or for the verification of existing ones, allowing the rapid and even real-time observation of the influence of the various changes made to the project.

Regarding the identification of defect in the electrical energy cables, in exploatation, usual or high-performance methods are used, based in particular on the phenomenon of reflection and refraction of the impulse transmitted in the cable, phenomenon generated by the impedance change at the defect location. In order to identify the defect, an important role is played by the existence of a current path on the cable route between the ends of the electrical cable and the place where the defect occurred. In the case of low voltage cables, there are situations where, following the sleeve process the continuity of the mechanical protection armature of the steel strip or the copper screen has not been restored. To measure the distance to the defect location, location equipment uses low and high voltage pulses which moves to the defect site with a certain speed and which is repeated after a selected time interval. These impulses are transmitted to the location of the defect at one end of the cable, through the circuit generated by the short circuit between the faulted conductor and the metal armature, which is usually found at ground potential. At the same time, there is situations where the defect is difficult to identify precisely because of the continuity of the reinforcement or screen and their connection to ground potential. This paper describes the stages of fault identification in a low-voltage power cable and presents a case study that highlights the importance of the metal reinforcement in the case of the high-voltage impulse method. Ways to detect defects using the arc reflected method (ARM) using the shock wave generator as well as the inductive method are also briefly presented.